BMW ActiveHybrid 7

BMW's hybrid system adds significant power to the 2011 ActiveHybrid 7, while making it the most fuel-efficient 7-series model. An active suspension gives the car excellent handling. Google local search integrates with the navigation system

Most automakers use the additional energy provided by a hybrid system to get away with a smaller gasoline engine, thereby maintaining expected power but reducing fuel use. BMW looked at that extra power and thought, "Excellent, we can make our cars go even faster!"

Such is the case with the 2011 BMW ActiveHybrid 7, which hosts the same engine as the standard BMW 750i, a twin turbo direct-injection 4.4-liter V-8, but straps on an electric motor getting power from a 120-volt lithium ion battery pack. The result: substantially more horsepower and better fuel.



BMW used the most recent Los Angeles Auto Show to display the production version of its new Activehybrid 7, the first product of its collaboration with Mercedes-Benz to produce a new mild hybrid system. While BMW and Mercedes partnered with Chrysler and General Motors on the more sophisticated two-mode hybrid that is now launching in the X6, the German's have also created an alternative lower cost and modular system. This mild hybrid will likely become the primary type used going forward for both of the German companies.

BMW told us that they developed the mild hybrid system to avoid some of the trade-offs inherent in other other systems. Among those are a significant loss of cargo space due the need to package the battery. In the case of the 7, the use of a new lithium ion battery has allowed the engineers to stuff it into a corner of the trunk. The hybrid only sacrifices 1.4 cubic feet of volume and reportedly can still accommodate four standard golf bags. The smaller battery only adds 62 pounds over the rear axle.

Like many automotive lithium ion applications, the unit in the 7 is actively cooled in order to maintain the battery at its optimum operating temperature. The BMW engineers have routed refrigerant from the air conditioning system through the battery to prevent it from overheating.

The big difference between the mild hybrid and the two-mode strong hybrid is in the transmission. The mild system is based on the new ZF 8-speed automatic transmission. BMW's powertrain engineers have been able take advantage of the electric motor's instant low-speed torque to make changes to the gearing on the hybrid, thus lowering engine speeds and improving efficiency. The 15 kW motor is sandwiched between the engine and torque converter. Because the electric motor provides much of the torque multiplication normally achieved through the fluid coupling, the engineers were able to use a smaller torque converter.

BMW ActiveHybrid technology also provides new features that promote efficiency while preserving comfort. As an example, the BMW ActiveHybrid 7 is the first BMW with automatic transmission to feature Auto Start Stop to maximize efficiency by avoiding engine idling when stopped. Another advantage is that the air conditioning and ventilation system remains fully operational when the vehicle is stopped and the engine is shut down. In this case, power is supplied directly through the 120-volt on-board network powered by the lithium-ion battery.

Special displays in the instrument cluster and the Central Display inform the passengers of the degree of efficiency and the current operating status of the hybrid components. The ActiveHybrid 7 is distinguished from the 750i by aerodynamically-tuned ten-spoke 19-inch light-alloy Aero wheels, and model designations on the trunk lid, C-pillars, and on the door cutouts. The BMW ActiveHybrid 7 is also available in special Bluewater Metallic exterior paintwork.

Like existing BMW 7 Series models, BMW’s first luxury sedan with ActiveHybrid technology will enter the market in two body variants. The extended version of BMW ActiveHybrid 7 has a wheelbase increased by 5.5", all of which is devoted to the enhanced comfort of rear-seat passengers. Both models are equipped with a high level of standard equipment and a wide range of options is also are available, thus enabling the ActiveHybrid 7 to be tailored the customers individual taste and requirements.

BMW ActiveHybrid: A key element of the BMW EfficientDynamics philosophy.

The BMW ActiveHybrid 7 takes an innovative approach to ensure outstanding efficiency in the segment. At the same time it offers dynamic driving characteristics at a level that one would expect from The Ultimate Driving Machine. BMW ActiveHybrid is an important element within the BMW EfficientDynamics philosophy meant to offer technologies able to significantly reduce fuel consumption and emissions on every new model while enhancing driving performance.

BMW uses hybrid technology because it can make an effective contribution to the reduction of fuel consumption and emissions. As a rule, the savings potential of hybrid technology increases with the power of the combustion engine interacting with the system. In the case of the BMW ActiveHybrid 7 precise coordination of the electric motor and the V8 serves to optimize the efficiency of the combustion engine under all operating conditions.

Germany Discovers Electricity
Let's not pretend that the 2011 BMW ActiveHybrid 7 is a truly eco-friendly alternative to the small car. Its rating for CO2 emissions on the European driving cycle is 219 g/km, more than double the 89 g/km rating of a Toyota Prius and roughly the same as a Porsche 911 Carrera. It might be a significant step forward from a 750i, which is rated at 266 g/km, but it's unlikely to gain a standing ovation at a tree-huggers' love-in. Let's remember that this is still a gargantuan sedan, measuring 205.2 inches overall and weighing 4,729 pounds when you choose the long-wheelbase version (a short-wheelbase ActiveHybrid 7 will be available, too).

Differentiate to first principles and the ActiveHybrid 7 is really a 750i with a twist. The twin-turbo, direct-injection, 4,395cc V8 is retained, but it's been retuned to develop 443 horsepower and 479 pound-feet of torque, while the standard 750i's V8 puts out 400 hp and 442 lb-ft of torque.

Just as with most other hybrid cars, the 2011 BMW ActiveHybrid 7 has regenerative brakes, so when you lift off the gas or apply the brakes, the small-capacity 0.4 kWh battery gets recharged. The location of the battery in the trunk does have a negative impact on the capacity of the (still mammoth) trunk, but BMW's engineers deemed it the best solution for crash safety and mass distribution. Overall, the hybrid 7 Series weighs just 130 pounds more than the standard 750i.

Mildly Hybriding
The ActiveHybrid 7 does not deliver a hybrid driving experience in the manner of a Toyota Prius or even this BMW's most obvious rival, the Lexus LS 600 h. The omnipresent operation of the V8 ensures that the basic experience is almost identical to any other gas-powered product of Bavaria. Indeed, you suspect that the plethora of dials and gizmos in the cabin are really there to remind those inside that they're riding in an alternative vehicle.

Our best advice is to ignore the power consumption meters and concentrate on the speedometer, because this 7 Series is comically quick. Luxury limos this big really have no right to hit 60 mph from rest in just 4.7 seconds. Lean on the throttle and the abundant urge of the twin-turbo V8 through the eight-speed transmission makes a mighty impression. Even above 100 mph on the autobahn, the ActiveHybrid keeps pulling and it scampers to its electronically limited top speed of 155 mph with effortless grace.

Some of the effect comes from the extra kick of the engine at peak rpm, even though the car has a taller final-drive ratio than a conventional 7 Series in order to maximize fuel economy.

Stop and Go
The only real novelty of driving the 2011 BMW ActiveHybrid 7 is the stop-start function. Pull to a stop with your foot on the brake and the engine will automatically stop, though the climate control and entertainment systems aren't affected and keep running because they're powered by the electronics system, not the engine. Release the brake and the V8 starts again. It's a familiar process, but it works exceptionally well here. There is something undeniable soothing about sitting in silence, we discovered.

BMW has yet to announce official fuel consumption figures for this car but is claiming a 15-17 percent improvement over a standard 750i. Over the test route of mixed autobahn and rural roads that we drove in Germany, we achieved a respectable (but hardly green) 19.7 mpg.

The ride and handling is unaffected by the green technology. The car's 50:50 weight distribution is retained and the extra mass makes scant difference in a car this big. As in the 750i, the car is supplemented by the electronic Dynamic Driving Control. This system allows you to toggle through four vehicle configurations — Comfort, Normal, Sport and Sport Plus. They comprise increasingly aggressive levels of damper control, steering assistance, antiroll bar stiffness, gearshift calibration, throttle gain and stability control. There is an appreciable difference between the settings of this quartet of modes, but the technology still feels slightly superfluous. Most drivers would be best advised to select Normal and forget about it.

For a luxo-barge, the 7 Series does a fine job of posing as a sport sedan. It's not as nimble as a 5 Series, of course, and you're always aware of its bulk, but it remains true to BMW's principles. The steering has more weight and feel than a Mercedes S-Class and fine body control is matched by a cosseting ride. This is still the driver's limo, even though the S-Class still has marginally better overall refinement.

Electrons Are Our Friends
The price for the 2011 BMW ActiveHybrid 7 has yet to be announced, but BMW North America is estimating a price of more than $100,000, a significant jump from the $80,455 price of a standard 750i. BMW is promising more standard equipment, though, and the exterior comes littered with ActiveHybrid badges to remind the world that you're a caring, sharing capitalist. BMW also expects this model to account for 10 percent of 7 Series sales in the U.S., a significant amount.

To be fair to BMW, it's not presenting this car as a solution to climate change. The 2011 BMW ActiveHybrid 7 is simply a means of retaining the performance and appeal of a top-end luxury car, whilst taking a slightly lower toll on the world's resources. Any technology that makes it slightly more practical or politically correct to drive a car as exciting as a BMW 7 Series should be hailed as a success.